JP2024061137A - Wireless communication system, management method for wireless communication system, and management device - Google Patents

Abstract

To provide a wireless communication system capable of suppressing excessive use of relay devices.SOLUTION: A wireless communication system includes: a high-level communication device that receives sensor data via 802.11ah wireless communication; a plurality of relay devices that relay the sensor data to the high-level communication device via 802.11ah wireless communication; and a plurality of sensor terminals that transmit the sensor data via 802.11ah wireless communication to a relay device selected from among the plurality of relay devices based on the transmission time per unit time of the relay devices.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wireless communication system, a management method for a wireless communication system, and a management device.

Patent Document 1 discloses a technology that, when fulfilling the role of a gateway between a sensor and a server, aggregates data between gateways while taking into account transmission time restrictions, thereby reducing the number of simultaneous connections to mobile communications by the gateway.

Patent Publication No. 6525323

In Japan, where the IEEE standard 802.11ah can be used, the 920 MHz band limits the transmission time per unit time (also called the transmission duty) to 10% under the Radio Law.

In wireless communication systems in which sensor data from multiple sensor terminals is transmitted to a higher-level communication device via a relay device, the relay device is likely to be used frequently.

The present invention has been made in consideration of the above problems, and its main objective is to provide a wireless communication system, a method for managing a wireless communication system, and a management device that can suppress excessive use of relay devices.

In order to solve the above problem, a wireless communication system according to one aspect of the present invention includes an upper communication device that receives sensor data via 802.11ah wireless communication, a plurality of relay devices that relay the sensor data to the upper communication device via 802.11ah wireless communication, and a plurality of sensor terminals that transmit the sensor data to a relay device selected from the plurality of relay devices based on the transmission time per unit time of the relay device via 802.11ah wireless communication. This makes it possible to suppress excessive use of the relay devices.

In the above aspect, the system may further include a server having a route management unit that acquires the transmission times per unit time of the multiple relay devices, and when the transmission time of a relay device on a predetermined route is equal to or greater than a threshold, changes the transmission destination of the sensor terminal to another relay device on a different route. This makes it possible to prevent excessive use of relay devices.

In the above aspect, the transmission destination may be changed to a relay device whose transmission time is less than the threshold. This makes it possible to prevent excessive use of the relay device.

In the above aspect, the sensor terminal may include the server, and the route management unit may transmit a route change request to the multiple relay devices to change the destination from the predetermined route to a relay device of the other route. This makes it possible to cause the relay device to change the route.

In the above aspect, the relay device included in the predetermined route may discard the pairing data representing the predetermined route in response to the route change request. This makes it possible to delete the pairing data from the relay device included in the predetermined route.

In the above aspect, the relay device included in the different route may generate pairing data representing the different route in response to the route change request. This makes it possible to generate pairing data for the relay device included in the different route.

In the above aspect, the higher-level communication device may transmit management data to the sensor terminal included in the predetermined route, and when the destination is changed from the predetermined route to the relay device of the other route, transmit the management data to the sensor terminal included in the other route. This makes it possible to suppress excessive use of the relay device due to the transmission of management data.

In the above aspect, the number of the plurality of sensor terminals may be greater than the number of the plurality of relay devices. This makes it possible to prevent excessive use of the relay device even in a situation where the frequency of use of the relay device is likely to increase.

In the above aspect, the threshold value may be smaller than the limit value of the transmission time per unit time. This makes it possible to change the route before the transmission time reaches the limit value.

In another aspect of the present invention, a method for managing a wireless communication system includes a higher-level communication device that receives sensor data via 802.11ah wireless communication, a plurality of relay devices that relay the sensor data to the higher-level communication device via 802.11ah wireless communication, and a plurality of sensor terminals that transmit the sensor data to one of the plurality of relay devices via 802.11ah wireless communication, and the plurality of sensor terminals transmit the sensor data to a relay device selected from the plurality of relay devices based on the transmission time per unit time of the relay device. This makes it possible to suppress excessive use of the relay devices.

In addition, a management device according to another aspect of the present invention includes a higher-level communication device that receives sensor data via 802.11ah wireless communication, a plurality of relay devices that relay the sensor data to the higher-level communication device via 802.11ah wireless communication, and a plurality of sensor terminals that transmit the sensor data to one of the plurality of relay devices via 802.11ah wireless communication, and includes an acquisition unit that acquires the transmission time per unit time of the plurality of relay devices, and a change unit that changes the route to another route that passes through another relay device when the transmission time of the relay device included in the predetermined route is equal to or greater than a threshold value. This makes it possible to suppress excessive use of the relay devices.

FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. FIG. 2 illustrates an example of the configuration of an access point. FIG. 2 illustrates an example of the configuration of a relay device. FIG. 2 is a diagram illustrating an example of the configuration of a sensor terminal. FIG. 11 is a diagram illustrating an example of pairing data for an access point. FIG. 11 is a diagram illustrating an example of pairing data for a relay device. FIG. 11 is a diagram illustrating an example of pairing data for a sensor terminal. FIG. 1 is a diagram for explaining a first embodiment. FIG. 2 illustrates an example of the configuration of a route management unit; FIG. 11 is a diagram illustrating an example of a procedure of a management method. FIG. 11 is a diagram for explaining a change in pairing data. FIG. 11 is a diagram for explaining a change in pairing data. FIG. 11 is a diagram for explaining a second embodiment. FIG. 2 illustrates an example of the configuration of a transmission management unit; FIG. 13 illustrates an example of a database. FIG. 13 is a diagram showing an example of a time table. FIG. 11 is a diagram illustrating an example of a procedure of a management method. FIG. 13 is a diagram for explaining a third embodiment. FIG. 13 illustrates an example of the configuration of a frequency management unit. FIG. 11 is a diagram illustrating an example of a procedure of a management method. FIG. 11 is a diagram illustrating an example of a procedure of a management method. FIG. 11 is a diagram illustrating an example of a procedure of a management method.

The following describes an embodiment of the present invention with reference to the drawings.

[System Overview]
1 is a block diagram showing an example of the configuration of a wireless communication system 100. The wireless communication system 100 includes an access point 1, one or more relay devices 2, and a plurality of sensor terminals 3. The wireless communication system 100 may further include a server 4.

The access point 1 and the server 4 are connected to a communication network, such as a wired LAN or the Internet. The access point 1 is an example of a higher-level wireless device. The higher-level wireless device is not limited to this, and may be, for example, a router.

The relay device 2 relays wireless communication between the access point 1 and the sensor terminal 3. The sensor terminal 3 is a wireless communication terminal equipped with a sensor, and transmits sensor data detected by the sensor. The sensor terminal 3 is a so-called IoT device.

The sensors used in the sensor terminal 3 include various sensors such as an optical sensor, an image sensor, a pressure sensor, a temperature sensor, a humidity sensor, or an acceleration sensor.

The access point 1, the relay device 2, and the sensor terminal 3 are capable of wireless communication using the 920 MHz band. Specifically, the access point 1, the relay device 2, and the sensor terminal 3 are capable of wireless communication using, for example, the IEEE standard 802.11ah.

The 920 MHz band is suitable for long-distance communications, and by having a relay device 2 between the access point 1 and the sensor terminal 3, the wireless communication system 100 is able to collect sensor data from a large number of sensor terminals 3 located over a wide area.

However, in the 920 MHz band, the Radio Law limits the transmission time per unit time (also called the transmission duty) to 10%. Specifically, the transmission time is limited to 6 minutes per hour.

Each sensor terminal 3 transmits sensor data via a route that passes through one relay device 2 to reach the access point 1 (hereinafter also referred to as the "upstream route"). That is, on the upstream route, the sensor data is transmitted from the sensor terminal 3 to the relay device 2, and then from the relay device 2 to the access point 1.

The access point 1 also transmits management data to the sensor terminal 3 via a route opposite to the upstream route (hereinafter also referred to as the "downstream route"). That is, on the downstream route, the management data is transmitted from the access point 1 to the relay device 2, and then from the relay device 2 to the sensor terminal 3.

Figure 2 is a block diagram showing an example of the configuration of the access point 1. The access point 1 includes a control unit 10, a wireless communication unit 11, and a wired communication unit 12.

The control unit 10 is a computer including a CPU, RAM, ROM, non-volatile memory, and an input/output interface. The CPU of the control unit 10 executes information processing according to a program loaded from the ROM or non-volatile memory to the RAM.

The program may be supplied via an information storage medium such as an optical disk or a memory card, or via a communications network such as the Internet or a LAN.

The wireless communication unit 11 enables wireless communication using the 920 MHz band. The wired communication unit 12 is connected to a wired LAN. The control unit 10 bridges the wireless communication terminal connected to the wireless communication unit 11 and the wired LAN connected to the wired communication unit 12.

Figure 3 is a block diagram showing an example of the configuration of the relay device 2. The relay device 2 includes a control unit 20 and a wireless communication unit 21. The control unit 20 and the wireless communication unit 21 have the same configuration as the control unit 10 and the wireless communication unit 11 of the access point 1.

Figure 4 is a block diagram showing an example of the configuration of the sensor terminal 3. The sensor terminal 3 includes a control unit 30, a wireless communication unit 31, and a sensor 33. The control unit 30 and the wireless communication unit 31 have the same configuration as the control unit 10 and the wireless communication unit 11 of the access point 1 described above.

The control unit 10 generates sensor data based on the electrical signal output from the sensor 33. The control unit 10 also changes settings based on the received management data. Note that the number of sensors 33 provided in the sensor terminal 3 is not limited to one, and may be multiple.

Figures 5 to 7 are diagrams showing examples of pairing data. Each of the access point 1, the relay device 2, and the sensor terminal 3 holds pairing data for defining the route along which the sensor data or management data is transmitted. The route defined in the pairing data includes both an upstream route and a downstream route. The pairing data is defined by the identifiers of the access point 1, the relay device 2, and the sensor terminal 3 on the route.

As shown in the example of FIG. 5, the pairing data for access point 1 includes data on a route that starts or ends at access point 1. When access point 1 receives management data from server 4, it refers to the pairing data and identifies the relay device 2 to which the management data is to be sent. For example, access point "AP" sends management data to relay device "RP1" included in route 1 for sending the management data to sensor terminal "ST1".

As shown in the example of FIG. 6, the pairing data for relay device 2 includes data on the route that passes through relay device 2. When relay device 2 receives management data from access point 1, it refers to the pairing data and identifies the sensor terminal 3 to which the management data is to be sent. For example, relay device "RP1" sends management data to sensor terminal "ST1" included in route 1 for sending the management data.

When the relay device 2 receives sensor data from the sensor terminal 3, it refers to the pairing data to identify the access point 1 to which the sensor data is to be transmitted. For example, the relay device "RP1" transmits the sensor data to the access point "AP" included in the route 1 for transmitting the sensor data from the sensor terminal "ST1".

As shown in the example of FIG. 7, the pairing data for the sensor terminal 3 includes data on a route that starts or ends at the sensor terminal 3. The sensor terminal 3 refers to the pairing data to identify the relay device 2 to which the sensor data is to be transmitted. For example, the sensor terminal "ST1" transmits sensor data to the relay device "RP1" included in the route 1 for transmitting the sensor data.

[First embodiment]
8 is a diagram for explaining the first embodiment. In this embodiment, a wireless communication system 100 includes a plurality of relay devices 2a and 2b. In this embodiment, a route management unit 5 is installed in each of a plurality of sensor terminals 3. The route management unit 5 is an example of a management device. For the sake of explanation, only one sensor terminal 3 is shown in the diagram, but the number of sensor terminals 3 is greater than the number of relay devices 2.

The route management unit 5 is not limited to being installed in the sensor terminal 3, but may be installed in, for example, a relay device 2, an access point 1, a server 4, or as an independent device.

When one sensor terminal 3 can communicate with two relay devices 2a and 2b, the routes by which the sensor terminal 3 transmits sensor data and receives management data can include route Ra via relay device 2a and route Rb via relay device 2b. Here, it is assumed that route Ra is used first.

Route Ra includes an upstream route along which sensor data is transmitted from the sensor terminal 3 to the relay device 2a, and then from the relay device 2a to the access point 1. Route Ra also includes a downstream route along which management data is transmitted from the access point 1 to the relay device 2a, and then from the relay device 2a to the sensor terminal 3.

Route Rb includes an upstream route along which sensor data is transmitted from the sensor terminal 3 to the relay device 2b, and then from the relay device 2b to the access point 1. Route Rb also includes a downstream route along which management data is transmitted from the access point 1 to the relay device 2b, and then from the relay device 2b to the sensor terminal 3.

However, in a system such as the wireless communication system 100 in which sensor data from a sensor terminal 3 is transmitted to an access point 1 via a relay device 2, data is concentrated in the relay device 2, so the transmission time of the relay device 2 is likely to increase compared to the sensor terminal 3 or the access point 1. This problem becomes more pronounced as the number of sensor terminals 3 increases.

Therefore, in this embodiment, excessive use of the relay device 2 is suppressed by changing the route depending on the usage history of the relay device 2 as described below.

Figure 9 is a block diagram showing an example of the configuration of the route management unit 5. The route management unit 5 is realized by the CPU of the sensor terminal 3 executing information processing according to a program. The route management unit 5 includes a transmission time acquisition unit 51 and a route change unit 52.

The transmission time acquisition unit 51 acquires the transmission time per unit time of the relay devices 2a and 2b. The relay devices 2a and 2b measure the transmission time per hour, and the transmission time acquisition unit 51 periodically acquires the current value of the transmission time per hour from the relay devices 2a and 2b. The transmission time per hour may be, for example, the transmission time in an hourly time frame, or the transmission time in the most recent hour.

When the transmission time of the relay device 2a included in the route Ra in use is equal to or greater than the threshold, the route change unit 52 changes to a route Rb that passes through another relay device 2b. That is, when the transmission time of the relay device 2a included in the route Ra in use is equal to or greater than the threshold based on the transmission time acquired by the transmission time acquisition unit 51, the route change unit 52 changes to another route Rb that passes through a relay device 2b whose transmission time is less than the threshold. The threshold is set to, for example, 8% of the transmission time of the unit time, with a margin of 10%. The threshold and the relay device 2b to be changed to may be determined based on the amount of data to be transmitted by the sensor terminal, the distance between the sensor terminal and the relay device, the transmission standby time of the sensor terminal, the time period, the weather, the wireless communication state including the number of communication errors, the number of times the threshold was reached in a certain period in the past, and the like.

The route change unit 52 transmits a route change request to change from route Ra to route Rb to the access point 1, the relay devices 2a and 2b, and the sensor terminal 3. When the access point 1, the relay devices 2a and 2b, and the sensor terminal 3 receive the route change request, they update the pairing data to change from route Ra to route Rb.

Figure 10 is a flow diagram showing an example of the procedure of a management method for the wireless communication system 100 according to the first embodiment. The CPU of the sensor terminal 3 functions as the route management unit 5 by executing the information processing shown in the figure according to a program.

The relay devices 2a and 2b transmit the current value of the transmission time (S21, S31). The relay devices 2a and 2b may periodically transmit the current value of the transmission time, for example, by including the current value of the transmission time in a beacon, or may transmit the current value of the transmission time in response to a periodic request from the route management unit 5.

The route management unit 5 acquires the current value of the transmission time from the relay devices 2a and 2b (S11, processing as the transmission time acquisition unit 51).

The route management unit 5 monitors the transmission time of the relay device 2a included in the route Ra in use, and when the transmission time of the relay device 2a becomes equal to or exceeds a threshold value (S12: YES), it executes route change processing (S13 to S15, processing as the route change unit 52).

It is preferable that the threshold be set smaller than the limit value for transmission time per unit time (specifically, 6 minutes per hour).

In the route change process, the route management unit 5 confirms that the transmission time of the other relay device 2b is less than the threshold (S13: YES), and then updates the pairing data held by the sensor terminal 3 (S14) and sends a route change request to the relay devices 2a and 2b (S15).

When there are multiple other relay devices 2b, the route management unit 5 selects the relay device 2b with the shortest transmission time from among the multiple relay devices 2b. Alternatively, the route management unit 5 may select the relay device 2b with the strongest radio wave intensity from among the multiple relay devices 2b.

The acquisition of the transmission time from the other relay device 2b in S11 may be performed when it is confirmed in S13 that the transmission time of the other relay device 2b is less than the threshold value.

When updating the pairing data in S14, the "relay device" portion of the pairing data (see FIG. 7), which is the destination of the sensor data, is changed from relay device 2a to relay device 2b.

When relay devices 2a and 2b receive a route change request (S22, S32: YES), they update the pairing data (S23, S33).

Specifically, in response to the route change request, the relay device 2a discards the pairing data representing the route Ra. For example, as shown in FIG. 11, in the pairing data of the relay device 2a, the data of the sensor terminal 3 (here, "ST3") that sent the route change request is discarded.

In addition, in response to the route change request, relay device 2b generates pairing data representing route Rb. For example, as shown in FIG. 12, data of the sensor terminal 3 (here, "ST3") that sent the route change request is newly generated in the pairing data of relay device 2b.

Similarly, the route management unit 5 also sends a route change request to the access point 1, and upon receiving the route change request, the access point 1 discards the pairing data representing route Ra in the pairing data (see FIG. 5) and generates pairing data representing route Rb.

By the above process, the route used is changed from route Ra to route Rb, and as a result, the sensor data from the sensor terminal 3 is sent to the access point 1 via the relay device 2b. In addition, the management data from the access point 1 is also sent to the sensor terminal 3 via the relay device 2b.

According to this embodiment, when the transmission time of relay device 2a included in the route Ra in use becomes equal to or exceeds a threshold, the route is changed to use another route Rb that passes through relay device 2b whose transmission time is less than the threshold, so that it is possible to prevent the transmission time of relay device 2a from exceeding the limit.

[Second embodiment]
13 is a diagram for explaining the second embodiment. In this embodiment, a transmission management unit 6 is installed in a server 4. The transmission management unit 6 is an example of a management device. In the figure, for ease of explanation, only one relay device 2 is shown, but there may be multiple relay devices 2.

The server 4 of the transmission management unit 6 is not limited to a server 4 on the network, but may be installed, for example, in an access point 1, a relay device 2, a sensor terminal 3, or as an independent device.

However, in a system such as the wireless communication system 100 in which sensor data from a sensor terminal 3 is transmitted to an access point 1 via a relay device 2, if the transmission timing of sensor data from multiple sensor terminals 3 is concentrated, there is a risk that the transmission time of the relay device 2 will exceed the limit.

Therefore, in this embodiment, the timing of transmission of sensor data by multiple sensor terminals 3 is managed as described below.

Figure 14 is a block diagram showing an example of the configuration of the transmission management unit 6. The transmission management unit 6 is realized by the CPU of the server 4 executing information processing according to a program. The transmission management unit 6 includes a determination unit 61 and a setting unit 62.

The determination unit 61 determines in advance the transmission timing at which the multiple sensor terminals 3 transmit sensor data. The setting unit 62 sets the transmission timing determined by the determination unit 61 to the multiple sensor terminals 3.

The determination unit 61 refers to a database (see FIG. 15) in which data related to the sensor data is stored, and determines the transmission timing for the multiple sensor terminals 3 to transmit the sensor data.

As shown in FIG. 15, the database includes fields such as "sensor terminal," "sensor data," "amount of data," and "transmission period." "Sensor terminal" represents the identifier of the sensor terminal 3.

"Sensor data" refers to sensor data transmitted by the sensor terminal 3. When one sensor terminal 3 has multiple sensors 33, multiple sensor data are associated with the sensor terminal 3.

"Data volume" indicates the volume of sensor data. The data volume does not need to be an exact value, and may be, for example, a guideline or grade of the data volume. "Transmission cycle" indicates the transmission cycle of the sensor data.

The determination unit 61 allocates the timing of transmitting sensor data to a time slot of a predetermined time (specifically, one hour) in the time table (see FIG. 16). Here, the predetermined time into which the time slots are divided is the same as the unit time in which the transmission time per unit time is limited in the 920 MHz band.

At this time, the decision unit 61 distributes the transmission timing by allocating the timing of transmission of sensor data by some sensor terminals 3 to a first time slot and the timing of transmission of sensor data by other sensor terminals 3 to a second time slot different from the first time slot. For example, as shown in FIG. 16, the sensor data D1, D2, and D4 of the sensor terminals ST1, ST2, and ST4 are allocated to the 14:00 time slot, and the sensor data D31 and D32 of the sensor terminal ST3 are allocated to the 15:00 time slot.

The determination unit 61 also allocates the timing of transmitting sensor data to a time slot, taking into consideration the transmission period of the sensor data stored in the database (see FIG. 15). For example, if the transmission periods T1 and T2 of the sensor data D1 and D2 are two hours, and the sensor data D1 and D2 are allocated to the time slots of 14:00 and 16:00, the other sensor data D31 and D32 are allocated to the time slot of 15:00, avoiding 14:00 and 16:00.

The determination unit 61 also limits the number of sensor data transmission timings to be allocated to one time slot to a predetermined number or less. For example, when the number of sensor data transmission timings to be allocated to one time slot is limited to three or less, if three pieces of sensor data D1, D2, and D4 are allocated to the 14:00 time slot, the other sensor data D31 and D32 are allocated to the 15:00 time slot.

The determination unit 61 also allocates the timing of transmitting sensor data to a time slot according to the amount of sensor data stored in the database (see FIG. 15). For example, if the sum of the data amounts A1, A2, and A4 of the sensor data D1, D2, and D4 is close to the amount of data for one hour, when the sensor data D1, D2, and D4 are allocated to the 14:00 time slot, the other sensor data D31 and D32 are allocated to the 15:00 time slot.

According to this embodiment, it is possible to distribute the timing of transmission of sensor data from multiple sensor terminals 3, thereby preventing the transmission time of the relay device 2 that relays the sensor data from exceeding a limit.

Figure 17 is a flow diagram showing an example of the procedure of a management method for the wireless communication system 100 according to the second embodiment. The CPU of the server 4 functions as the transmission management unit 6 by executing the information processing shown in the figure according to a program.

The following describes an example of a process for determining the timing of transmitting sensor data when a new sensor terminal 3 is added, or when a new sensor 33 is added to any of the sensor terminals 3. The present invention is not limited to this, and the timing of transmitting sensor data may be determined simultaneously.

When the sensor terminal 3 detects an addition (S51: YES), it notifies the transmission management unit 6 of the addition (S52). That is, the sensor terminal 3 notifies the transmission management unit 6 of the addition when the sensor terminal 3 is installed or when a new sensor 33 is added to the sensor terminal 3.

When the transmission management unit 6 is notified of the expansion from the sensor terminal 3 (S41: YES), it determines the transmission timing for the sensor terminal 3 to transmit sensor data (S42, processing as the determination unit 61) and notifies the sensor terminal 3 of the determined transmission timing (S43, processing as the setting unit).

As described above, the transmission timing is determined taking into consideration the transmission timing of sensor data by other sensor terminals 3 in the time table (see FIG. 16). In other words, the transmission timing of new sensor data is determined so that the transmission timings of multiple sensor data are distributed and not concentrated in a specific time frame.

When the sensor terminal 3 is notified of the transmission timing from the transmission management unit 6 (S51: YES), it sets the notified transmission timing (S52). After that, when the set transmission timing arrives, the sensor terminal 3 transmits the sensor data to the relay device 2.

As a result, when a new sensor terminal 3 is added, or when a new sensor 33 is added to any sensor terminal 3, it is possible to determine the timing of transmitting the new sensor data so as not to coincide with the timing of transmitting sensor data from the other sensor terminals 3.

[Third embodiment]
18 is a diagram for explaining the third embodiment. In this embodiment, a frequency management unit 7 is installed in the server 4. The frequency management unit 7 is an example of a management device. In the figure, for ease of explanation, only one relay device 2 is shown, but there may be multiple relay devices 2.

The frequency management unit 7 is not limited to being installed in the server 4, but may be installed in, for example, the access point 1, the relay device 2, the sensor terminal 3, or as an independent device.

However, in a system such as the wireless communication system 100 in which sensor data from a sensor terminal 3 is transmitted to an access point 1 via a relay device 2, the frequency of transmission of the sensor data may vary depending on the urgency, etc., and if the transmission frequency increases excessively, there is a risk that the transmission time of the relay device 2 will exceed the limit.

Therefore, in this embodiment, excessive use of relay device 2 is suppressed by balancing the frequency of sensor data transmission as described below.

FIG. 19 is a block diagram showing an example of the configuration of the frequency management unit 7. The frequency management unit 7 is realized by the CPU of the server 4 executing information processing. The frequency management unit 7 includes a monitoring unit 71 and a change unit 72.

The monitoring unit 71 monitors the frequency of transmission of sensor data from the multiple sensor terminals 3. When the frequency of transmission of sensor data from one of the multiple sensor terminals 3 (hereinafter referred to as "sensor terminal 3a") increases, the change unit 72 decreases the frequency of transmission of sensor data from the other sensor terminal 3 (hereinafter referred to as "sensor terminal 3b").

The monitoring unit 71 may detect an increase in the frequency of transmission of sensor data from the sensor terminal 3a when the frequency of transmission of the sensor data becomes equal to or exceeds a threshold value, when the rate of change in the frequency of transmission of the sensor data becomes equal to or exceeds a threshold value, or when the differential value of the frequency of transmission of the sensor data becomes equal to or exceeds a threshold value.

In addition, when the monitoring unit 71 receives a notification from the sensor terminal 3a that the frequency of transmission of sensor data has increased, the monitoring unit 71 may detect the increase in the frequency of transmission of sensor data from the sensor terminal 3a.In addition, the monitoring unit 71 may determine the urgency level based on the sensor data from multiple sensor terminals 3.

The change unit 72 instructs the sensor terminal 3b to reduce the frequency of transmitting sensor data. When the sensor terminal 3b receives an instruction to reduce the transmission frequency from the frequency management unit 7, the sensor terminal 3b reduces the frequency of transmitting sensor data. The change unit 72 may also stop the transmission of sensor data from the sensor terminal 3b.

FIGS. 20 to 22 are flow diagrams showing an example of the procedure of a management method for the wireless communication system 100 according to the third embodiment. The CPU of the server 4 functions as a frequency management unit 7 by executing the information processing shown in the figures according to a program. Detailed explanations of overlapping steps may be omitted by assigning the same numbers to the steps.

Figure 20 is a flow diagram of the first example. The sensor terminal 3a determines the urgency level based on the sensor data (S71), and if an emergency state is detected, i.e., if the urgency level is equal to or higher than a predetermined level (S72: YES), the sensor terminal 3a increases the frequency of transmitting the sensor data (S73).

The sensor terminal 3a periodically performs such a determination of the urgency. The urgency is the urgency of the object monitored by the sensor 33, and is expressed, for example, in a rank according to the magnitude of the sensor data value.

The frequency management unit 7 monitors the frequency of transmission of sensor data (S61, processing as the monitoring unit 71), and when it detects an increase in the frequency of transmission of sensor data by the sensor terminal 3a (S62: YES), it determines the sensor terminal 3b for which the transmission frequency is to be reduced (S63) and instructs the sensor terminal 3b to reduce the transmission frequency (S64: processing as the change unit 72).

If there are multiple sensor terminals 3 other than sensor terminal 3a, the frequency management unit 7 determines the sensor terminal 3 with the lowest urgency determined based on, for example, the sensor data as the sensor terminal 3b for which the transmission frequency is to be reduced.

When the sensor terminal 3b receives an instruction to reduce the transmission frequency from the frequency management unit 7 (S81: YES), it reduces the transmission frequency of the sensor data (S82).

Figure 21 is a flow diagram of the second example. The sensor terminal 3a determines the urgency level based on the sensor data (S71), and if an emergency state is detected (S72: YES), increases the transmission frequency of the sensor data (S73) and transmits a notification of the increased transmission frequency to the frequency management unit 7 (S74). The notification of the increased transmission frequency is also a notification of the emergency state.

When the frequency management unit 7 receives a notification of an increase in the transmission frequency (S65: YES), it determines the sensor terminal 3b for which the transmission frequency is to be decreased (S63) and instructs the sensor terminal 3b to decrease the transmission frequency (S64). When the sensor terminal 3b receives an instruction to decrease the transmission frequency from the frequency management unit 7 (S81: YES), it decreases the transmission frequency of the sensor data (S82).

Figure 22 is a flow diagram of the third example. The frequency management unit 7 monitors the sensor data of multiple sensor terminals 3, and determines whether any of the sensor terminals 3 is in an emergency state, i.e., whether the urgency level is a predetermined level or higher, based on the sensor data (S66 to S67, processing as the monitoring unit 71).

When the frequency management unit 7 detects a sensor terminal 3a whose urgency level is equal to or higher than a predetermined level (S67: YES), it notifies the sensor terminal 3a of an emergency state (S68). The notification of an emergency state also instructs the sensor terminal 3a to increase the transmission frequency. When the sensor terminal 3a receives a notification of an emergency state from the frequency management unit 7 (S75: YES), it increases the transmission frequency of sensor data (S73).

Furthermore, the frequency management unit 7 determines the sensor terminal 3b, which has a low level of urgency, as a target for reducing the transmission frequency (S63), and instructs the sensor terminal 3b to reduce the transmission frequency (S64). When the sensor terminal 3b receives the instruction to reduce the transmission frequency from the frequency management unit 7 (S81: YES), it reduces the transmission frequency of the sensor data (S82).

According to this embodiment, when the frequency of transmission of sensor data from the sensor terminal 3a increases, the frequency of transmission of sensor data from the sensor terminal 3b is decreased, making it possible to prevent the transmission time of the relay device 2 that relays the sensor data from exceeding the limit. Furthermore, it is possible to prevent the sensor terminal 3a in an emergency state from being unable to transmit sensor data.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible for those skilled in the art. In addition, the above-described multiple embodiments can be combined as appropriate.

Representative embodiments of the present invention are listed below.

(1)
A higher-level communication device that receives sensor data via 802.11ah wireless communication;
a plurality of relay devices that relay the sensor data to the higher-level communication device by wireless communication using IEEE 802.11ah;
a plurality of sensor terminals each configured to transmit the sensor data to a relay device selected from the plurality of relay devices based on a transmission time per unit time of the relay device by wireless communication using IEEE 802.11ah;
A wireless communication system comprising:

(2)
a server having a route management unit that acquires transmission times per unit time of the plurality of relay devices, and changes a transmission destination of a sensor terminal to another relay device on a different route when the transmission time of a relay device on a predetermined route is equal to or greater than a threshold value;
A wireless communication system as described in (1).

(3)
the route management unit changes the destination to a relay device whose transmission time is less than a threshold.
A wireless communication system as described in (2).

(4)
The sensor terminal includes the server,
the route management unit transmits a route change request to the plurality of relay devices to change a destination from the predetermined route to a relay device of the different route;
A wireless communication system according to (2) or (3).

(5)
the relay device included in the predetermined route discards pairing data representing the predetermined route in response to the route change request;
A wireless communication system according to (4).

(6)
the relay device included in the different route generates pairing data representing the different route in response to the route change request;
A wireless communication system as described in (4).

(7)
the higher level communication device transmits management data to the sensor terminal included in the predetermined route, and when a destination is changed from the predetermined route to the relay device of the different route, transmits the management data to the sensor terminal included in the different route.
A wireless communication system according to any one of (2) to (6).

(8)
the number of the plurality of sensor terminals is greater than the number of the plurality of relay devices;
A wireless communication system according to any one of (1) to (7).

(9)
The threshold value is smaller than the limit value of the transmission time per unit time.
A wireless communication system according to any one of (1) to (8).

(10)
In a wireless communication system including an upper communication device that receives sensor data via 802.11ah wireless communication, a plurality of relay devices that relay the sensor data to the upper communication device via 802.11ah wireless communication, and a plurality of sensor terminals that transmit the sensor data to one of the plurality of relay devices via 802.11ah wireless communication, the plurality of sensor terminals transmit the sensor data to a relay device selected from the plurality of relay devices based on a transmission time per unit time of the relay device,
A method for managing a wireless communication system.

(11)
an acquisition unit for acquiring transmission times per unit time of the plurality of relay devices in a wireless communication system including: an upper communication device that receives sensor data via 802.11ah wireless communication; a plurality of relay devices that relay the sensor data to the upper communication device via 802.11ah wireless communication; and a plurality of sensor terminals that transmit the sensor data to one of the plurality of relay devices via 802.11ah wireless communication;
a change unit that changes the route to another route that passes through another relay device when the transmission time of the relay device included in the predetermined route is equal to or greater than a threshold;
A management device comprising:

Reference Signs List 1 Access point (example of upper communication device), 2 Relay device, 3 Sensor terminal, 4 Server, 5 Route management unit, 6 Transmission management unit, 7 Frequency management unit, 10 Control unit, 11 Wireless communication unit, 12 Wired communication unit, 20 Control unit, 21 Wireless communication unit, 30 Control unit, 31 Wireless communication unit, 33 Sensor, 51 Transmission time acquisition unit, 52 Route change unit, 61 Determination unit, 62 Setting unit, 71 Monitoring unit, 72 Change unit

Claims (11)

A higher-level communication device that receives sensor data via 802.11ah wireless communication;
a plurality of relay devices that relay the sensor data to the higher-level communication device by wireless communication using IEEE 802.11ah;
a plurality of sensor terminals each configured to transmit the sensor data to a relay device selected from the plurality of relay devices based on a transmission time per unit time of the relay device by wireless communication using IEEE 802.11ah;
A wireless communication system comprising: a server having a route management unit that acquires transmission times per unit time of the plurality of relay devices, and changes a transmission destination of a sensor terminal to another relay device on a different route when the transmission time of a relay device on a predetermined route is equal to or greater than a threshold value;
2. The wireless communication system according to claim 1. the route management unit changes the destination to a relay device whose transmission time is less than a threshold.
3. The wireless communication system according to claim 2. The sensor terminal includes the server,
the route management unit transmits a route change request to the plurality of relay devices to change a destination from the predetermined route to a relay device of the different route;
3. The wireless communication system according to claim 2. the relay device included in the predetermined route discards pairing data representing the predetermined route in response to the route change request;
5. The wireless communication system according to claim 4. the relay device included in the different route generates pairing data representing the different route in response to the route change request;
5. The wireless communication system according to claim 4. the higher level communication device transmits management data to the sensor terminal included in the predetermined route, and when a destination is changed from the predetermined route to the relay device of the different route, transmits the management data to the sensor terminal included in the different route.
3. The wireless communication system according to claim 2. the number of the plurality of sensor terminals is greater than the number of the plurality of relay devices;
2. The wireless communication system according to claim 1. The threshold value is smaller than the limit value of the transmission time per unit time.
2. The wireless communication system according to claim 1. In a wireless communication system including an upper communication device that receives sensor data via 802.11ah wireless communication, a plurality of relay devices that relay the sensor data to the upper communication device via 802.11ah wireless communication, and a plurality of sensor terminals that transmit the sensor data to one of the plurality of relay devices via 802.11ah wireless communication, the plurality of sensor terminals transmit the sensor data to a relay device selected from the plurality of relay devices based on a transmission time per unit time of the relay device,
A method for managing a wireless communication system. an acquisition unit for acquiring transmission times per unit time of the plurality of relay devices in a wireless communication system including: an upper communication device that receives sensor data via 802.11ah wireless communication; a plurality of relay devices that relay the sensor data to the upper communication device via 802.11ah wireless communication; and a plurality of sensor terminals that transmit the sensor data to one of the plurality of relay devices via 802.11ah wireless communication;
a change unit that changes the route to another route that passes through another relay device when the transmission time of the relay device included in the predetermined route is equal to or greater than a threshold;
A management device comprising:

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